SpaceX has already launched dozens of Starlink satellites to date, but not without some controversy. When the satellites were first launched, they weren't properly oriented in orbit. In some cases, their solar panels were facing toward Earth, which made the objects appear far brighter than they would ordinarily be.
This proved to be quite a headache for astronomers, as they rely on relatively clear Earth-to-space visibility to do their jobs properly. Fortunately, after the solar panels were re-oriented toward the Sun, the brightness faded considerably.
Even with the problem reduced (but not outright eliminated), Musk nonetheless promised that SpaceX will do its best to make sure Starlink has "no material effect" on space discoveries moving forward, and now he's keeping his word.
In a couple of hours, SpaceX will send 60 more Starlink satellites into orbit (you can watch the launch live above), and one of those satellites will contain a deployable Sun "visor" that will attempt to block sunlight reflectivity.
It's unclear how effective this shield will be, but if it does its job and successfully reduces satellite visibility from Earth, it will be a "permanent fixture" for Starlink launches in the future.